CENP-E is essential for reliable bioriented spindle attachment, but chromosome alignment can be achieved via redundant mechanisms in mammalian cells
CENP-E is essential for reliable bioriented spindle attachment, but chromosome alignment can be achieved via redundant mechanisms in mammalian cells
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DOI：
10.1091/mbc.12.9.2776
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发表时间：
2001-09-01
影响因子：
3.3
通讯作者：
Yen, TJ
中科院分区：
文献类型：
--
作者：
McEwen, BF;Chan, GKT;Yen, TJ
CENP-E是一种驱动蛋白样蛋白，当从哺乳动物动粒中耗尽时，其导致有丝分裂停滞，具有对齐和未对齐染色体的混合物。在本研究中，我们使用免疫荧光，视频和电子显微镜，以证明CENP-E从着丝粒通过抗体微量注射消耗减少着丝粒微管结合23%对齐染色体，并严重减少微管结合在未对齐染色体。CENP-E功能的破坏也降低了跨着丝粒的张力，增加了纺锤体极片段化的发生率，并导致单取向染色体异常地接近纺锤体极。然而，染色体显示出典型的聚集、快速向极运动和振荡运动模式。此外，对齐和未对齐染色体的动粒表现出检查点蛋白定位的正常模式。这些数据解释了一个模型，其中冗余的机制，使着丝粒微管结合和检查点监测的CENP-E在着丝粒的情况下，但减少微管结合效率，加剧了在纺锤体极定位不良，导致慢性单取向的染色体和有丝分裂停滞。纺锤体内的染色体位置似乎是着丝粒CENP-E功能的关键决定因素。
CENP-E is a kinesin-like protein that when depleted from mammalian kinetochores leads to mitotic arrest with a mixture of aligned and unaligned chromosomes. In the present study, we used immunofluorescence, video, and electron microscopy to demonstrate that depletion of CENP-E from kinetochores via antibody microinjection reduces kinetochore microtubule binding by 23% at aligned chromosomes, and severely reduces microtubule binding at unaligned chromosomes. Disruption of CENP-E function also reduces tension across the centromere, increases the incidence of spindle pole fragmentation, and results in monooriented chromosomes approaching abnormally dose to the spindle pole. Nevertheless, chromosomes show typical patterns of congression, fast poleward motion, and oscillatory motions. Furthermore, kinetochores of aligned and unaligned chromosomes exhibit normal patterns of checkpoint protein localization. These data are explained by a model in which redundant mechanisms enable kinetochore microtubule binding and checkpoint monitoring in the absence of CENP-E at kinetochores, but where reduced microtubule-binding efficiency, exacerbated by poor positioning at the spindle poles, results in chronically monooriented chromosomes and mitotic arrest. Chromosome position within the spindle appears to be a critical determinant of CENP-E function at kinetochores.